“One or more ArcGIS ver. 9.3.170 products exist” Be sure that all other ESRI products are uninstalled before doing this – 1. Browse to your ArcGIS Server 9.3 installation location (should be C:\Program Files\ArcGIS) and delete the entire ArcGIS folder. If you want to use your 9.3 Server configuration files for the 10.1 Server, copy C:\Program files\ArcGIS\Server to a different location.